1. Field of the Invention The field of the invention is replaceable cutting bits for cutting metal and plastic, and more particularly cutting bits for a sign engraving machine.
2. Description of the Background Art
It is typical in machines for cutting metal and plastic to have some type of replaceable cutter blade. There are, however, many designs for such blades and their holders, and substantial commercial advantages can inure to those products which exemplify superior designs.
Soviet Patent Abstract SU 1484-478-A shows a milling cutter with two cutting knives pivoted around a common pivot to adjust the distance between their cutting tips, which are formed as corners of the cutting knives. This changes the angle of the blades relative to the cutting surface without teaching any particular advantageous angular relationships.
Other milling and boring cutters disclosed in U.S. Pat. Nos. 3,814,536; 4,595,320 and 4,645,383 have used replaceable inserts in which an entire edge or side of the cutter body provides the cutting edge. These cutters have utilized means such as Allen-head screws for fixing the cutter inserts in the cutter head. This, in turn, requires the use of tools when replacing worn out cutter inserts with a new set.
The present invention was made in response to a need to provide blades, which were easily replaceable without the use of special tools, which exhibit reasonable operating life, and which are especially suited for cutting metal or plastic in sign engraving operations.